linux-kernel - [syzbot] [kvm?] KMSAN: uninit-value in em_ret

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Message-ID: <0000000000009c91ce060e87575b@google.com>
Date: Tue, 09 Jan 2024 10:18:33 -0800
From: syzbot <syzbot+579eb95e588b48b4499c@...kaller.appspotmail.com>
To: bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com, 
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org, mingo@...hat.com, 
	pbonzini@...hat.com, seanjc@...gle.com, syzkaller-bugs@...glegroups.com, 
	tglx@...utronix.de, x86@...nel.org
Subject: [syzbot] [kvm?] KMSAN: uninit-value in em_ret_far

Hello,

syzbot found the following issue on:

HEAD commit:    2cf4f94d8e86 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=144e8d01e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4a65fa9f077ead01
dashboard link: https://syzkaller.appspot.com/bug?extid=579eb95e588b48b4499c
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/589557edbfd5/disk-2cf4f94d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f2480533f00e/vmlinux-2cf4f94d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9463e8eac2ed/bzImage-2cf4f94d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+579eb95e588b48b4499c@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in em_ret_far+0x332/0x340 arch/x86/kvm/emulate.c:2258
 em_ret_far+0x332/0x340 arch/x86/kvm/emulate.c:2258
 x86_emulate_insn+0x1d81/0x5800 arch/x86/kvm/emulate.c:5289
 x86_emulate_instruction+0x13c5/0x3090 arch/x86/kvm/x86.c:9101
 kvm_mmu_page_fault+0x100a/0x1120 arch/x86/kvm/mmu/mmu.c:5778
 handle_ept_violation+0x4ef/0x7e0 arch/x86/kvm/vmx/vmx.c:5788
 __vmx_handle_exit arch/x86/kvm/vmx/vmx.c:6567 [inline]
 vmx_handle_exit+0x1b01/0x2130 arch/x86/kvm/vmx/vmx.c:6584
 vcpu_enter_guest arch/x86/kvm/x86.c:10992 [inline]
 vcpu_run arch/x86/kvm/x86.c:11095 [inline]
 kvm_arch_vcpu_ioctl_run+0x9d4f/0xc680 arch/x86/kvm/x86.c:11321
 kvm_vcpu_ioctl+0xbfc/0x1770 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4155
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0x225/0x410 fs/ioctl.c:857
 __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Local variable eip created at:
 em_ret_far+0x3a/0x340 arch/x86/kvm/emulate.c:2243
 x86_emulate_insn+0x1d81/0x5800 arch/x86/kvm/emulate.c:5289

CPU: 0 PID: 5010 Comm: syz-executor207 Not tainted 6.7.0-rc6-syzkaller-00010-g2cf4f94d8e86 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
=====================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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If the report is already addressed, let syzbot know by replying with:
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